1. Field of the Invention
The present invention relates to a method and circuit for converting the image format of n-line, three-dimensional electronic images produced with line polarization into m-line images whose respective, immediately neighboring two lines are respectively polarized in alternation into first and second directions upon viewing, wherein all lines polarized in the first direction are employed for the presentation of a first sub-image and all lines polarized in the second direction are employed for the presentation of a second sub-image.
2. Description of the Prior Art
The line polarization method utilizes the interlace method in televisions transmissions. In the interlace method, a first and a second field are always transmitted in alternation, these being combined in a comb-like fashion to form an image.
Two images, one for each of the eyes of the person, are needed in three-dimensional viewing, these being offset relative to one another in conformity with the respectively different viewing angle of each eye relative to the motive. The two fields in the television transmission can respectively present one of these images, whereby one field is polarized in a first direction and the other field is polarized in a second direction. This, for example, can be achieved with a polarization filter on the field pane of the image presentation device that polarizes the individual lines into the one and other direction in alternation. When this is the case, one can view three-dimensionally with corresponding eyeglasses that filter out the one image for the one eye and the other image for the other eye.
The different resolution standards in which images are transmitted represent a current problem. Known resolution standards are, for example, 625 lines in the PAL transmission method, 1250 lines in the HDTV transmission method and 575 lines in the PAL plus transmission method. When an electronic image presentation device is designed for one of these standards and this same image presentation device is also prepared to polarize the individual presentation lines into the one and other direction in alternation for three-dimensional image presentation, a three-dimensional image transmitted in a different resolution standard can no longer be presented. The reason for this is because allocation of polarized lines of the image presentation device and the transmitted fields no longer coincides.
The publication by Jxc3xcgen Ost, xe2x80x9cBildfernsprechen, kompatibel mit der Fernsehrundfunknorm,xe2x80x9d In Radio Mentos Elektronik, 1975, No. 5, pages 194-196, discloses a method for converting the image format of 313-line electronic images into 625-line images by repeating every line. No measures are addressed in order to be able to produce three-dimensional images in the conversion with line polarization.
German patent document DE 32 34 557 C2 describes a xe2x80x9c1250/100/4:1 standardxe2x80x9d that is intended to enable HDTV and 3D reproduction. This standard is based on the fact that frames are respectively composed of four sub-images that are written on a color television screen in mutually offset grids with a sub-image frequency corresponding to twice the power supply frequency.
It is therefore an object of the invention to specify a method and circuit arrangements for the conversion of the image format of three-dimensional electronic images produced with line polarization.
Accordingly, pursuant to the method and circuit of the present invention, a correct allocation of transmitted fields to the polarized lines of the image presentation device is always established regardless of the resolution standard with which the images are transmitted and displayed. Missing lines are supplemented. Too many lines are skipped. The correct allocation of the transmitted image lines to the respective, polarized presentation lines, finally is obtained by a line transposition when necessary.
Accordingly, in an embodiment of the present invention, a method is provided for converting an image format of n-line, three-dimensional electronic images produced with line polarization into m-line images whose respective, immediately neighboring two lines are respectively polarized in alternation into a first and second direction upon viewing, wherein all lines polarized in the first direction are employed for the presentation of a first sub-image and all lines polarized in the second direction are employed for the presentation of a second sub-image, given that the first and second sub-images are needed for three-dimensional viewing, the method including the steps of: abbreviating as a whole number a fraction formed of the values n and m having the form m/n to form mxe2x80x2/nxe2x80x2; dividing the lines of the image to be converted into first groups having a respective line plurality nxe2x80x2; combining two of the first groups which abut one another to respective second groups, wherein a last first group remaining by itself is combined with an imaginary dummy group of the same size having nothing but dummy lines to form a last second group; determining |p| lines to be inserted, if mxe2x80x2 greater than nxe2x80x2, twice per respective second group in the conversion according to an equation |p|=|mxe2x80x2xe2x88x92nxe2x80x2|; determining |p| lines to be skipped, if mxe2x80x2 less than nxe2x80x2, twice per respective second group in the conversion according to the equation |p|=|mxe2x80x2xe2x88x92nxe2x80x2|; inserting |p| lines, if mxe2x80x2 greater than nxe2x80x2, twice in each of the second group wherein two successive lines are always affected by an insertion and, given an odd-numbered |p|, the last line not yet affected by an insertion is affected by an insertion in the one first group in a meeting area of the first groups abutting one another in a respective second group, and the first line not yet affected by an insertion is affected by an insertion in the other group; inserting |p| lines, if mxe2x80x2 greater than nxe2x80x2, twice in each of the second group wherein two successive lines are always affected by a skipping and, given an odd-numbered |p|, the last line not yet affected by a skipping is affected by a skipping in the one first group in a meeting area of the first groups abutting one another in a respective second group, and the first line not yet affected by a skipping is affected by a skipping in the other group; and transposing with one another in sequence the two inward lines of the four-line groups respectively arising after an addition of lines to two successive lines of the second group.
In an embodiment of the method, the inserted lines are copied from preceding or following lines.
In an embodiment of the method, the inserted lines are interpolated from preceding and succeeding lines.
In an embodiment of the method, the lines within a second group affected by an insertion or a skipping are selected uniformly distributed within the respective second group.
In an embodiment of the method, the lines polarized in the one direction are shifted relative to one another in a plane compared to the lines polarized in the other direction.
In an embodiment, the method further includes the step of setting a mode, wherein each even-numbered or odd-numbered line is overwritten with the content of a preceding line, for switching from a three-dimensional image to a two-dimensional image.
In a further embodiment of the present invention, a circuit is provided for presenting a three-dimensional image electronically generated upon application of a line polarization method from a video signal adjacent an input, the circuit including: a frequency converter having a set frequency which defines a plurality of presented lines; at least one parallel delay line exhibiting an independent delay value and having a controlled switch for activating or deactivating the respective delay line provided for the image presentation; and control electronics for controlling switches, wherein image lines are transposed as warranted and controls for the switches of the delay lines are provided.
In yet another a further embodiment of the present invention, a circuit is provided for presenting a three-dimensional image electronically generated upon application of a line polarization method from a video signal adjacent an input, the circuit including: a digital write-read memory for simultaneously storing at least one three-dimensional image in digital form; and a controller circuit, the controller circuit for fetching the stored images at a rate dependent on the storing, wherein stored lines are read out in a different sequence and forwarded for image presentation.
Additional features and advantages of the present invention are described in, and will be apparent from, the Detailed Description of the Preferred Embodiments and the Drawing.